Wednesday, September 11, 2024
The low-frequency hum emanating from the bitcoin data center in Hood County has been a topic of conversation for more than a year, drawing attention from local, national and even international news outlets.
Countless residents have claimed the sound — caused by massive cooling fans used to keep the computers from overheating — has been the source of numerous health issues like vertigo, migraines, ear infections and nausea.
However, according to a recent sound study published by the company, the facility’s noise levels are now significantly below legal limits.
While this recent development may suggest improvements, it has prompted mixed reactions from the community as some residents continue to voice their concerns about the ongoing impact of the sound on their daily lives.
SOUND STUDY
According to the MARA Granbury website, an independent, third-party sound survey was conducted around the data center July 18, revealing that noise levels measured between 43-63 decibels — well-below the state and county law noise limit of 85 decibels.
Sound is measured in decibels (dB), a unit that quantifies the intensity or loudness of sound. According to the MARA Granbury website, the sound study used to measure the sound for the plant used the “A-weighted” decibels (dBA) scale because it reflects the sensitivity of the human ear to different frequencies of sound. Due to this reason, dBA is considered to be a more accurate measure of perceived loudness for humans.
The sound survey was carried out by Absolute Noise Control between 11 a.m. and 5 p.m., with sound receivers strategically positioned at 11 different sites around the operational data center. These receivers measured the sound levels during the facility's operation, with the reported figures representing 15-minute average levels.
The results indicated that all locations around the Hood County data center recorded sound levels well below the legal limit of 85 dB, as stated on the Granbury MARA website.
“As part of our commitment to transparency, we have also voluntarily compared our sound measurements to Granbury’s quiet hours limit, even though this limit does not apply to our operations since the Hood County data center is located outside of Granbury,” the report states. “Even when compared to Granbury’s noise limit during quiet hours of 65 dB, the sound measurements near the data center are all within acceptable limits.”
MITIGATION EFFORTS
MARA, formerly known as Marathon Digital Holdings, acquired the site in January and took operational control in April. At that point, a noise and vibration consulting firm called Cerjan conducted an initial sound study. The results from that study showed a reading of 78 dB, indicating that sound levels have declined since MARA took ownership of the data center earlier this year.
"When we purchased the site, we were not aware that there were noise concerns from the neighbors,” MARA’s Director of Communication Ellie Atherton told the Hood County News. “When we first came on board in April and began operating the site and started to hear from the neighbors, we wanted to do our own due diligence and understand like, what we were actually operating at that time when we were at full capacity, and there were still multiple other miners that were hosted there as well.”
Atherton explained that although MARA was still operating under the legal limit, the company wanted to do “anything they could” to mitigate any community concerns.
"As a company, being within legal limits is basically the least we can do,” she said. “We want to be a long-term partner for the community. We want to be contributing in a meaningful way and be a good neighbor, so us just being within legal limits is like basically the baseline of what we could be doing.”
To maintain compliance with noise regulations, the company implemented a number of different processes and procedures to try to bring the sound levels down.
According to Atherton, the biggest contributor to sound at the site is the air-cooled miners. While she couldn't specify the exact number in operation at the time, she said the company committed to converting at least 50% of the site to immersion mining. This technique involves submerging the miners in a nonconductive dielectric fluid, which not only minimizes dust and maintenance but also significantly dampens noise.
“It required a major capital investment on our side,” she explained. “Immersion mining technology and equipment is extremely expensive, but I think for us, being a good neighbor and a long-term partner to the community was really important to us, so we voluntarily decided to convert 50% of the site to immersion cooling.”
Since then, the company has been gradually deactivating air-cooled containers, with 95 of them now offline completely.
"We are currently at about a third of the capacity we were at when in April, so about two-thirds of the air-cooled miners have come offline since April,” Atherton explained. “The immersion mining technology is beginning to be installed, but it has not come online yet. We will start turning that on beginning at the end of this month, so the number of air-cooled containers and air-cooled miners will never increase from what it is right now. We will actually continue to bring more air-cooled miners offline and bring more immersion cooling online.”
While sound levels vary at other MARA facilities based on operational capacity, Atherton explained that a similar site located in Abu Dhabi that operates entirely with immersion cooling technology has never received any noise complaints, despite being in the “heart” of Masdar City.
“We're very confident that the conversion to immersion cooling is going to make a huge difference here,” she said.
PROACTIVE PLANS
Although MARA has achieved significant advancements in reducing noise levels, the company still intends to maintain its efforts, as many changes are set to take place in the coming months.
Atherton said MARA will be breaking ground on a new sound wall later this month. Last November, previous owner US Bitcoin erected a 24-foot-high and almost 2,000-foot-long soundproofing wall. However, many residents reported that sound levels did not improve, attributing this to the fact that the wall only covered a portion of the site.
“In our new sound study, you can actually see that the readings taken just outside of the sound wall where it currently exists are significantly lower than anywhere else on our perimeter,” she explained. “So, we're going to build a sound wall that'll cover the rest of our perimeter to make sure that even with the immersion cooling that we're blocking out even more sound than we are right now.”
By the end of this month, the company expects to have converted 20% of its site to liquid immersion cooling, with plans to reach 30% by September, 40% by October and 50% by December.
Updates to the sound wall are projected for completion in October. In November, MARA plans to start planting trees and enhance the landscape. By December, 100 to 110 air-cooled containers are expected to be deactivated.
RESIDENT FEEDBACK
Since MARA shared its sound study findings on social media, numerous residents have raised doubts about the study's legitimacy. Some commenters questioned the accuracy of the results, alleging that MARA intentionally timed the survey during a low operational period rather than during peak hours. Others wondered if the testing conditions were adjusted to reflect lower noise levels.
Atherton clarified that the company did not select a specific date and time for the study, but that it was scheduled based on the testing firm's availability. She also addressed the residents' claims and stated they are inaccurate.
"While our site is at a decreased capacity right now, it has been at a decreased capacity for months, and that is part of our effort to make it quieter there,” she said. “We did not change our capacity or operations for the purpose of conducting this sound study. All of the environmental factors, the coordinates, the temperature, humidity percentages, weather, that is all recorded in the sound study to provide context, to make sure that if anyone ever looks at it, then they can adjust in any way for any environmental factors. There is analysis in that report as well that talks about how those environmental factors could contribute, but the short story is, there wasn't much weather that day, so it didn't have a huge impact.”
Atherton reported that many journalists have also reached out to MARA indicating residents have claimed the sound has become louder since April. However, she stressed that this claim is also false.
“Objectively, we have data to show that that's simply not the case,” she said. “There are other people in the community that have thanked us for providing the data and can testify to the fact that things have gotten quieter. We're trying to do a lot of work with the community to be good neighbors. We have a Facebook page, and that's where we seem to get the most feedback and engagement from the community."
Another common area of concern, Atherton said, is the sound reading conducted by Precinct 2 Constable John Shirley, which was brought up during a public court trial July 8 involving former site manager David Fischer.
"Over the course of the trial, the constable was actually found to have manipulated that sound data,” Atherton said. “But people are really clinging to that number. Something that we've been working to correct in any way that we can is that those numbers were not true. There are sound experts that testified in that same case that the way that he was using that machine, it could not have been getting accurate readings.”
Additionally, she mentioned that Constellation Energy, the partner providing power to the site, conducted its own sound readings recently to ensure compliance with legal limits. According to Atherton, its findings also aligned closely with MARA's results.
Constellation Energy isn’t the only entity conducting additional sound studies on the bitcoin plant, however.
During a Hood County Commissioners Court meeting July 23, the court voted 3:2 to commission its own independent sound study. The court declared HGC Engineering: Noise, Vibration & Acoustical Consulting Services to be the most qualified firm to conduct the study, with expenses not to exceed $6,500.
“Hood County has commissioned an independent sound study,” Precinct 2 Commissioner Nannette Samuelson told the Hood County News. “We look forward to receiving the results.”
With Hood County funding its own sound study, Atherton expressed hope that study will reflect the truth, assuring residents that MARA is committed to staying within legal limits and actively working to improve conditions at the site.
"I have confidence that the truth will come out and that people will see that we are not only within legal limits, but that we are truthfully making significant efforts and strides to make their lives better and make the site better — and I hope that they will see that eventually,” she said.
Atherton emphasized that MARA is taking community concerns seriously, particularly regarding claims about its operational noise levels.
"We are investing a lot of money voluntarily, time and resources to make improvements here and make the lives of the surrounding residents better,” she said. “It's very important to us that we continue to be good neighbors and contribute in any way that we can. While we aren't operating at the levels that other people have claimed, it doesn't mean that we are taking any of this less seriously. It doesn't mean that we are going to throw our hands up and say, ‘Well, we're within the legal limits, so we're fine.’ It's really important for the community to support us, and for us to support them.”
For more information on the sound study, visit maragranbury.com. If you have questions, concerns or suggestions, send an email to granbury@mara.com or reach out via the MARA Granbury Data Center Facebook page.
